It's not just vitamins and minerals. They also want to regulate herbal supplements in much the same way as prescription drugs.
This is a good example of where the democratic process has completely failed. Almost no members of the general public are asking for this ban, and the numbers of people who have actually been harmed by overdosing on vitamins and supplements is miniscule. It's essentially a solution looking for a problem.
The groups that are pushing for this ban are doctors who want to extend the power and reach of their (already too powerful) profession, and drugs companies who want to prevent patients from having access to cheaper, mostly non-patentable alternatives to their overpriced products. The whole thing stinks.
However, I think it would be a tactical error for us to focus our limited energies on overturning this ban. We really ought to be focusing on the bigger prize of reforming the prescription system itself. If a mechanism existed that enabled patients to obtain drugs without the need for a doctor's prescription (obviously at their own risk and expense) then a lot of our problems would disapper.
Let's face it, the difficulties most of us face in obtaining prescriptions is one of the major sources of friction between us and the medical profession. And such a change would actually reduce risk to patients because we would no longer be forced to take our chances with internet pharmacies.